<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>高兴</title>

    <style>
        html, body {
            margin: 0px;
            width: 100%;
            height: 100%;
            overflow: hidden;
            background: #000;
        }

        #canvas {
            width: 100%;
            height: 100%;
        }
    </style>

</head>
<body>

<canvas id="canvas"></canvas>
<script>
    function initVars() {

        pi = Math.PI;
        ctx = canvas.getContext("2d");
        canvas.width = canvas.clientWidth;
        canvas.height = canvas.clientHeight;
        cx = canvas.width / 2;
        cy = canvas.height / 2;
        playerZ = -25;
        playerX = playerY = playerVX = playerVY = playerVZ = pitch = yaw = pitchV = yawV = 0;
        scale = 600;
        seedTimer = 0;
        seedInterval = 5, seedLife = 100;
        gravity = .02;
        seeds = new Array();
        sparkPics = new Array();
        s = "https://cantelope.org/NYE/";
        for (i = 1; i <= 10; ++i) {
            sparkPic = new Image();
            sparkPic.src = s + "spark" + i + ".png";
            sparkPics.push(sparkPic);
        }
        sparks = new Array();
        pow1 = new Audio(s + "pow1.ogg");
        pow2 = new Audio(s + "pow2.ogg");
        pow3 = new Audio(s + "pow3.ogg");
        pow4 = new Audio(s + "pow4.ogg");
        frames = 0;
    }

    function rasterizePoint(x, y, z) {

        var p, d;
        x -= playerX;
        y -= playerY;
        z -= playerZ;
        p = Math.atan2(x, z);
        d = Math.sqrt(x * x + z * z);
        x = Math.sin(p - yaw) * d;
        z = Math.cos(p - yaw) * d;
        p = Math.atan2(y, z);
        d = Math.sqrt(y * y + z * z);
        y = Math.sin(p - pitch) * d;
        z = Math.cos(p - pitch) * d;
        var rx1 = -1000, ry1 = 1, rx2 = 1000, ry2 = 1, rx3 = 0, ry3 = 0, rx4 = x, ry4 = z,
            uc = (ry4 - ry3) * (rx2 - rx1) - (rx4 - rx3) * (ry2 - ry1);
        if (!uc) return {x: 0, y: 0, d: -1};
        var ua = ((rx4 - rx3) * (ry1 - ry3) - (ry4 - ry3) * (rx1 - rx3)) / uc;
        var ub = ((rx2 - rx1) * (ry1 - ry3) - (ry2 - ry1) * (rx1 - rx3)) / uc;
        if (!z) z = .000000001;
        if (ua > 0 && ua < 1 && ub > 0 && ub < 1) {
            return {
                x: cx + (rx1 + ua * (rx2 - rx1)) * scale,
                y: cy + y / z * scale,
                d: Math.sqrt(x * x + y * y + z * z)
            };
        } else {
            return {
                x: cx + (rx1 + ua * (rx2 - rx1)) * scale,
                y: cy + y / z * scale,
                d: -1
            };
        }
    }

    function spawnSeed() {

        seed = new Object();
        seed.x = -50 + Math.random() * 100;
        seed.y = 25;
        seed.z = -50 + Math.random() * 100;
        seed.vx = .1 - Math.random() * .2;
        seed.vy = -1.5;//*(1+Math.random()/2);
        seed.vz = .1 - Math.random() * .2;
        seed.born = frames;
        seeds.push(seed);
    }

    function splode(x, y, z) {

        t = 5 + parseInt(Math.random() * 150);
        sparkV = 1 + Math.random() * 2.5;
        type = parseInt(Math.random() * 3);
        switch (type) {
            case 0:
                pic1 = parseInt(Math.random() * 10);
                break;
            case 1:
                pic1 = parseInt(Math.random() * 10);
                do {
                    pic2 = parseInt(Math.random() * 10);
                } while (pic2 == pic1);
                break;
            case 2:
                pic1 = parseInt(Math.random() * 10);
                do {
                    pic2 = parseInt(Math.random() * 10);
                } while (pic2 == pic1);
                do {
                    pic3 = parseInt(Math.random() * 10);
                } while (pic3 == pic1 || pic3 == pic2);
                break;
        }
        for (m = 1; m < t; ++m) {
            spark = new Object();
            spark.x = x;
            spark.y = y;
            spark.z = z;
            p1 = pi * 2 * Math.random();
            p2 = pi * Math.random();
            v = sparkV * (1 + Math.random() / 6)
            spark.vx = Math.sin(p1) * Math.sin(p2) * v;
            spark.vz = Math.cos(p1) * Math.sin(p2) * v;
            spark.vy = Math.cos(p2) * v;
            switch (type) {
                case 0:
                    spark.img = sparkPics[pic1];
                    break;
                case 1:
                    spark.img = sparkPics[parseInt(Math.random() * 2) ? pic1 : pic2];
                    break;
                case 2:
                    switch (parseInt(Math.random() * 3)) {
                        case 0:
                            spark.img = sparkPics[pic1];
                            break;
                        case 1:
                            spark.img = sparkPics[pic2];
                            break;
                        case 2:
                            spark.img = sparkPics[pic3];
                            break;
                    }
                    break;
            }
            spark.radius = 25 + Math.random() * 50;
            spark.alpha = 1;
            spark.trail = new Array();
            sparks.push(spark);
        }
        switch (parseInt(Math.random() * 4)) {
            case 0:
                pow = new Audio(s + "pow1.ogg");
                break;
            case 1:
                pow = new Audio(s + "pow2.ogg");
                break;
            case 2:
                pow = new Audio(s + "pow3.ogg");
                break;
            case 3:
                pow = new Audio(s + "pow4.ogg");
                break;
        }
        d = Math.sqrt((x - playerX) * (x - playerX) + (y - playerY) * (y - playerY) + (z - playerZ) * (z - playerZ));
        pow.volume = 1.5 / (1 + d / 10);
        pow.play();
    }

    function doLogic() {

        if (seedTimer < frames) {
            seedTimer = frames + seedInterval * Math.random() * 10;
            spawnSeed();
        }
        for (i = 0; i < seeds.length; ++i) {
            seeds[i].vy += gravity;
            seeds[i].x += seeds[i].vx;
            seeds[i].y += seeds[i].vy;
            seeds[i].z += seeds[i].vz;
            if (frames - seeds[i].born > seedLife) {
                splode(seeds[i].x, seeds[i].y, seeds[i].z);
                seeds.splice(i, 1);
            }
        }
        for (i = 0; i < sparks.length; ++i) {
            if (sparks[i].alpha > 0 && sparks[i].radius > 5) {
                sparks[i].alpha -= .01;
                sparks[i].radius /= 1.02;
                sparks[i].vy += gravity;
                point = new Object();
                point.x = sparks[i].x;
                point.y = sparks[i].y;
                point.z = sparks[i].z;
                if (sparks[i].trail.length) {
                    x = sparks[i].trail[sparks[i].trail.length - 1].x;
                    y = sparks[i].trail[sparks[i].trail.length - 1].y;
                    z = sparks[i].trail[sparks[i].trail.length - 1].z;
                    d = ((point.x - x) * (point.x - x) + (point.y - y) * (point.y - y) + (point.z - z) * (point.z - z));
                    if (d > 9) {
                        sparks[i].trail.push(point);
                    }
                } else {
                    sparks[i].trail.push(point);
                }
                if (sparks[i].trail.length > 5) sparks[i].trail.splice(0, 1);
                sparks[i].x += sparks[i].vx;
                sparks[i].y += sparks[i].vy;
                sparks[i].z += sparks[i].vz;
                sparks[i].vx /= 1.075;
                sparks[i].vy /= 1.075;
                sparks[i].vz /= 1.075;
            } else {
                sparks.splice(i, 1);
            }
        }
        p = Math.atan2(playerX, playerZ);
        d = Math.sqrt(playerX * playerX + playerZ * playerZ);
        d += Math.sin(frames / 80) / 1.25;
        t = Math.sin(frames / 200) / 40;
        playerX = Math.sin(p + t) * d;
        playerZ = Math.cos(p + t) * d;
        yaw = pi + p + t;
    }

    function rgb(col) {

        var r = parseInt((.5 + Math.sin(col) * .5) * 16);
        var g = parseInt((.5 + Math.cos(col) * .5) * 16);
        var b = parseInt((.5 - Math.sin(col) * .5) * 16);
        return "#" + r.toString(16) + g.toString(16) + b.toString(16);
    }

    function draw() {

        ctx.clearRect(0, 0, cx * 2, cy * 2);

        ctx.fillStyle = "#ff8";
        for (i = -100; i < 100; i += 3) {
            for (j = -100; j < 100; j += 4) {
                x = i;
                z = j;
                y = 25;
                point = rasterizePoint(x, y, z);
                if (point.d != -1) {
                    size = 250 / (1 + point.d);
                    d = Math.sqrt(x * x + z * z);
                    a = 0.75 - Math.pow(d / 100, 6) * 0.75;
                    if (a > 0) {
                        ctx.globalAlpha = a;
                        ctx.fillRect(point.x - size / 2, point.y - size / 2, size, size);
                    }
                }
            }
        }
        ctx.globalAlpha = 1;
        for (i = 0; i < seeds.length; ++i) {
            point = rasterizePoint(seeds[i].x, seeds[i].y, seeds[i].z);
            if (point.d != -1) {
                size = 200 / (1 + point.d);
                ctx.fillRect(point.x - size / 2, point.y - size / 2, size, size);
            }
        }
        point1 = new Object();
        for (i = 0; i < sparks.length; ++i) {
            point = rasterizePoint(sparks[i].x, sparks[i].y, sparks[i].z);
            if (point.d != -1) {
                size = sparks[i].radius * 200 / (1 + point.d);
                if (sparks[i].alpha < 0) sparks[i].alpha = 0;
                if (sparks[i].trail.length) {
                    point1.x = point.x;
                    point1.y = point.y;
                    switch (sparks[i].img) {
                        case sparkPics[0]:
                            ctx.strokeStyle = "#f84";
                            break;
                        case sparkPics[1]:
                            ctx.strokeStyle = "#84f";
                            break;
                        case sparkPics[2]:
                            ctx.strokeStyle = "#8ff";
                            break;
                        case sparkPics[3]:
                            ctx.strokeStyle = "#fff";
                            break;
                        case sparkPics[4]:
                            ctx.strokeStyle = "#4f8";
                            break;
                        case sparkPics[5]:
                            ctx.strokeStyle = "#f44";
                            break;
                        case sparkPics[6]:
                            ctx.strokeStyle = "#f84";
                            break;
                        case sparkPics[7]:
                            ctx.strokeStyle = "#84f";
                            break;
                        case sparkPics[8]:
                            ctx.strokeStyle = "#fff";
                            break;
                        case sparkPics[9]:
                            ctx.strokeStyle = "#44f";
                            break;
                    }
                    for (j = sparks[i].trail.length - 1; j >= 0; --j) {
                        point2 = rasterizePoint(sparks[i].trail[j].x, sparks[i].trail[j].y, sparks[i].trail[j].z);
                        if (point2.d != -1) {
                            ctx.globalAlpha = j / sparks[i].trail.length * sparks[i].alpha / 2;
                            ctx.beginPath();
                            ctx.moveTo(point1.x, point1.y);
                            ctx.lineWidth = 1 + sparks[i].radius * 10 / (sparks[i].trail.length - j) / (1 + point2.d);
                            ctx.lineTo(point2.x, point2.y);
                            ctx.stroke();
                            point1.x = point2.x;
                            point1.y = point2.y;
                        }
                    }
                }
                ctx.globalAlpha = sparks[i].alpha;
                ctx.drawImage(sparks[i].img, point.x - size / 2, point.y - size / 2, size, size);
            }
        }
    }

    function frame() {

        if (frames > 100000) {
            seedTimer = 0;
            frames = 0;
        }
        frames++;
        draw();
        doLogic();
        requestAnimationFrame(frame);
    }

    //时间监听，页面尺寸改变
    window.addEventListener("resize", function () {

        canvas.width = canvas.clientWidth;
        canvas.height = canvas.clientHeight;
        cx = canvas.width / 2;
        cy = canvas.height / 2;
    });

    initVars();
    frame();
</script>

</body>
</html>

